Anisotropic Outward Force‐Induced Construction of 2D Monolayered Macroporous Fe−N−C Catalysts with Enhanced Mass Transfer for Efficient Oxygen Reduction

Abstract While micropores can effectively accommodate Fe−N 4 active sites for Fe−N−C catalysts, only those Fe−N 4 sites near the external surface are efficiently utilized. Herein, geometry engineering is conducted on a N‐doped graphene quantum dots (N‐GQDs) derived 2D monolayered macroporous carbon nanosheet‐based Fe−N−C catalyst (Fe‐MaPCS) to enhance its catalytic performance. The unique 2D monolayered carbon nanosheet, favorable for electron and mass transfer, is initially achieved by pyrolyzing a 2D Fe 3+ /N‐GQDs hybrid precursor. Subsequently, anisotropic outward force‐induced pore engineering triggers the creation of interconnected macropores, significantly enlarging the external surface area and enabling the high accessibility of micropore‐hosted Fe−N 4 sites. The unique 2D macroporous architecture of the optimized Fe‐MaPCS‐100 is crucial for facilitating mass transfer, leading to remarkable oxygen reduction reaction performance with a half‐wave potential of 0.904 V versus. RHE, significantly surpassing its micropore‐dominated counterpart (Fe‐MiPCS). Molecular dynamics simulations further confirm that the oxygen flow velocity in Fe‐MaPCS‐100 is 3.4 times higher than that of Fe‐MiPCS, consistent with the distribution of relaxation time analysis and calculated results, thereby validating the enhanced mass transfer efficiency by the 2D macroporous architecture.